In telephony, ringback or a ringback signal is an audible tone or series of tones or an audible message or other like signal provided to a calling party's telephone or other device or end user terminal (EUT) to indicate that the called party's EUT is receiving a ringing signal or is otherwise being alerted. Traditionally, in wire-line networks such as those conforming to the ETSI standards, the ringback signal is generated and/or provided by a telecommunications switch within the PSTN (Public Switched Telephone Network). For example, the switch may be a class 5 telecommunications switch such as Lucent Technologies 5ESS or another like switch. The ringback signal is commonly provided by the switch serving the called party, and the ringback signal is the same for all calls.
More recently, customized ringback services have been introduced in telecommunications networks. Using such a service, a called party subscriber is able to choose which one of a plurality of different ringback signals are played or provided to a calling party based upon one or more determinate factors.
For example, with reference to FIG. 1, a calling party 10 being served by a switch or SSP (Service Switching Point) 12 places a call over the PSTN 20 to a called party 30 being served by a switch or SSP 32. Suitably, the customized ringback signals are generated and/or provided by a service node (SN) 34 operatively connected to the SSP 32, e.g., via trunks or other like transmission channels. Assuming the called party 30 subscribes to the customized ringback service, when the call placed by the calling party 10 makes its appearance at the SSP 32 (i.e., via the PSTN 30), the SSP 32 detects that special handling is to be provided by the SN 34. Accordingly, the SSP 32 extends the call to the SN 34 via one of the trunks (e.g., trunk 36). Traditionally, the SN 34 initiates a second leg of the call for the called party using a separate trunk (e.g., trunk 38), and in parallel, provides the subscriber selected ringback signal to the calling party 10. When the called party 30 answers the call, the SN 34 “bridges” or otherwise connects the two legs of the call together, as indicated by the hairpin or arrow 40.
As can be appreciated from the above example, call hair-pinning at the SN 34 in the manner shown unduly ties-up various resources. For example, the two trunks 36 and 38 are both occupied for the duration of the call. Moreover, resources within the SN 34 (e.g., ports, conference circuits, etc.) also remain used for the entire duration of the call. Accordingly, it is desirable to circumvent or bypass call hair pinning and/or extricate the SN 34 from participation in the call after the called party 30 has answered the call. That is to say, it is desirable to have a “call drop back” feature or function, whereby once the called party 30 has answered the call, the two call legs are bridged at the SSP 32 rather that being hair-pinned in the SN 34, thereby allowing the SN 34 to be dropped out of the call.
In an Advanced Intelligent Network (AIN) such as the kind used in the North American Region, there have been developed standards and/or techniques to avoid call hair-pinning at the service node. For example, there are known Telcordia specification of TBCT (Two B Channel Transfer) and the Nortel-specific RLT (Release Link Trunk) approach. However, there have been heretofore no similar standards or approaches developed in or for ETSI networks that provide the desired call drop back functionality.
Accordingly, a new and improved method and/or system for providing a customized ringback service without hair pinning at the SN is disclosed that overcomes the above-referenced problems and others.